An article having a substrate, such as an optical article, a display or an optical recording medium, is required to have properties such as water/oil repellency or stain removability so that water or fouling (such as fingerprints, sebum, sweat, cosmetics, foods, etc.) is less likely to attach on the surface, or that fouling, if has attached on the surface, can easily be removed. For example, if fouling attaches on the surface of an eyeglass lens, visibility tends to be impaired and visual quality tends to be deteriorated. If fouling attaches on the surface of an optical recording medium, a trouble is likely to be caused in recording or reproducing a signal. If fouling attaches on the surface of a display, the visibility tends to be low, and in the case of a display provided with a touch panel, the operation efficiency tends to be adversely affected.
As improvement techniques for an aluminum oxide substrate surface, a technique for forming a surface layer from a phosphate compound having a perfluoroalkyl group, such as 1H,1H,2H,2H-perfluorodecylphosphonic acid (Non-Patent Document 1), has been known.